SHORT COMMUNICATION Eur J Biol 2019; 78(2): 165-168 The Effect of Body Shape Type on Differentiability of Traditional and Geometric Morphometric Methods: A Case Study of Channa gachua (Hamilton, 1822) Atta Mouludi-Saleh1 , Soheil Eagderi1 , Hadi Poorbagher1 , 1 Shirin Kazemzadeh 1University of Tehran, Faculty of Natural Resources, Department of Fisheries, Karaj, Iran ORCID IDs of the authors: A.M.S. 0000-0002-0939-0901; S.E. 0000-0001-8649-9452; H.P. 0000-0003-0546-8713; S.K. 0000-0003-0253-4148 Please cite this article as: Mouludi Saleh A, Eagderi S, Poorbagher H, Kazemzadeh S. The Effect of Body Shape Type on Differentiability of Traditional and Geometric Morphometric Methods: A Case Study of Channa gachua (Hamilton, 1822). Eur J Biol 2019; 78(2): 165-168. DOI: 10.26650/EurJBiol.2019.0011 ABSTRACT Objective: The morphological differences of two populations of the Dwarf snakehead, Channa gachua (Hamilton, 1822) from Sarbaz (Makran basin) and Halil (Hamun-e Jaz Murian basin) rivers were studied using geometric and traditional morphometrics (GM and TM) methods to test the hypothesis that the type of body shape can produce different results. Materials and Methods: A total of 16 landmark-points and 12 distance measurements were defined to analyse the body shape differences and the extracted data were analyzed using GM and TM methods. Results: Our findings reject the hypothesis, and the results revealed that GM is more effective in detecting meticulous morphological differences. Conclusion: In addition, the results suggest selecting a proper method i.e. GM or TM, based on the degree of accuracy needed i.e. if we need to find small shape differences within its signification, GM is a superior technique, or to show the type of differences, then we can use TM. Keywords: Freshwater Fish, Morphology, Phenotypic Plasticity, Generalized Procrustes Analysis INTRODUCTION It bring to us this hypothesis that such differences may be related to the body shape type of the studied Comparative studies on the body shape in fishes are organisms. For instance, if a fish’s body shape is simple, commonly used to understand many aspects such as then we can expect similar results of both TM and GM resource management, evolution, behaviour, ecology methods; and if the body shape is complex, then we and phenotype plasticity (1-6). In many works, which can expect a different result. Therefore, this study was have investigated the morphological variation of the conducted to compare the body shape of the dwarf biological structures using traditional (TM) (7-9) and snakehead, Channa gachua, using TM and GM methods. geometric morphometric (GM) (10-17) techniques, it has been suggested that GM is more effective to detect Channa gachua is a species with large head scales and morphological disparities (4, 8). Additionally, it have elongate dorsal and anal fins, and with the ability to been shown that both methods can lead to similar (12) breathe from air inhabiting tropical and sub-tropical or different results (9). water bodies (18). It is a fish species with a bottom rover Address for Correspondence: Soheil Eagderi E-mail: [email protected] Submitted: 29.05.2019 • Revision Requested: 24.07.2019 • Last Revision Received: 20.08.2019 • Accepted: 04.09.2019 © Copyright 2019 by The Istanbul University Faculty of Science • Available online at http://ejb.istanbul.edu.tr • DOI: 10.26650/EurJBiol.2019.0011 165 Eur J Biol 2019; 78(2): 165-168 Mouludi Saleh et al. The Traditional and Geometric Morphometric Methods of the Dwarf Snakehead Figure 1. Defined landmark-points to extract the body shape data of Channa gachua. (1) anterior-most point of the snout tip on the upper jaw, (2) center of the eye, (3) dorsal edge of the head perpendicular to the center of eye, (4) origin and (5) insertion point of the dorsal-fin base, (6) postero-dorsal end of the caudal peduncle at its connection to the caudal fin, (7) posterior end of the medial region of the caudal peduncle, (8) postero-ventral end of the caudal peduncle at its connection to the caudal fin, (9) insertion and (10) origin point of the anal-fin base, (11) most anterior point of the pectoral fin, (12) posterior edge of the opercle, (13) ventral end of the gill slit, (14) the line extends perpendicularly to the most basic part of the gill slit above the head, (15) The terminus of the oral clefts in the upper jaw and (16) ventral edge of the head perpendicular to the center of eye. body shape pattern i.e. a simple body shape that expects the same results of both TM and GM methods. The biggest population of this species in the western Asia, is found in the Makran, Mashkid and Hamun-e Jaz Murian basins of Iran (18). Where M(t) is standardized values of characters, M(0) = characters MATERIALS AND METHODS of the observed length L = standard length mean of all samples, L(0) = a standard length of each sample and b = regression In total, 40 specimens of C. gachua representing two different coefficient between log L(0) and log M(0). populations were collected from the Halil (n= 17, 28°40'29.43"N, 57°42'22.96"E, Hamun-e Jaz Murian basin) and Sarbaz (n= Analyses for GM method were performed using PAST and 23, 26°37'47"N, 61°15'31"E, Makran basin) rivers using an MorphoJ (version 1.01) softwares. Levin’s test and DFA/ electrofishing device (Samus MP750). After anesthesia, the Hotelling’s T-test in TM method were performed in SPSS V.19 left sides of the fresh collected specimens were photographed and PAST software, respectively. using a copy-stand equipped with a digital camera (Kodak EasyShare Z650 with a 6 MP resolution) with fins erected by RESULTS AND DISCUSSION insect pins. Then, the sampled specimens were fixed in the Geometric Method buffered formalin and transferred to a laboratory. DFA and Hotelling’s T-test showed that the two populations For the GM method, a total of 16 homologous landmark-points can be significantly differentiated in terms of the body shape were digitized using tpsDig2 software (version 2.16) (Figure 1) (P>0.0001) (Figure 2). The wireframe of the body shape showed on 2D pictures. A Generalized Procrustes analysis (GPA) was differences in position of the snout and caudal peduncle length. used to remove non-shape data, including size, position and In the Halil River population, the body was deeper and the eyes direction. The resulting data were analyzed using discriminant function analysis (DFA) and Hotelling’s T-test to investigate the morphological distinction between the populations. Morphological disparities between the populations were visualized using deformation grids in MorphoJ software. For the TM method, 12 distance measurements, including SL (standard length), SnL (snout length), ED (eye horizontal diameter), HL (head length), HW (maximum head width), HDO (head depth at posterior edge of the opercle), HDE (head depth at middle of the eye), BD (body depth at dorsal-fin origin), DFL (dorsal-fin length), AFL (anal-fin length) and CPL (caudal peduncle length) were taken using dial calipers to the nearest 0.1 mm. To remove the size from data, they were standardized Figure 2. Discriminant function analysis of Channa gachua using the Beacham formula as following (19): populations from the Halil and Sarbaz rivers in GM method. 166 167 Eur J Biol 2019; 78(2): 165-168 Mouludi Saleh et al. The Traditional and Geometric Morphometric Methods of the Dwarf Snakehead Table 1. Levin’s test and mean (± standard deviation) of each morphological character measured in Channa gachua from Sarbaz and Halil rivers populations (All measurements are shown in mm. Variables for which significant differences were obtained are highlighted in bold). Characters Sarbaz River (mean±SD) Halil River (mean±SD) F P-value SL 98.48±0.00 98.48±0.00 - SnL 4.28±0.94 4.48±1.19 7.37 0.01 ED 4.4±0.43 4.29±0.98 12.92 0.001 HL 29.98 ±2.03 30.1 ±2.47 2.86 0.98 HW 21.09±0.83 20.96±0.99 1.61 0.212 HDO 19.14±1.02 18.93±1.1 0.401 0.53 HDE 10.05±0.84 10.12±0.91 1.31 0.294 BH 19.81±1.27 19.49±1.20 0.085 0.772 DFL 53.12±1.38 53.04±1.3 0.074 0.788 AFL 33.81±1.79 33.24±1.19 1.93 0.177 CPL 8.5±0.90 8.3±0.87 0.029 0.885 AFL = anal-fin length, BD = body depth at dorsal-fin origin, CPL = caudal peduncle length, DFL = dorsal-fin length, ED = eye horizontal diameter, HDE = head depth at middle of the eye, HDO = head depth at posterior edge of the opercle, HL = head length, HW = maximum head width, SnL = snout length, and SL = standard length. and snout had a more ventral position than those of the Sarbaz Morphological variations in fishes are considered to be an River one (Figure 3). important adaptive strategy for populations experiencing inconsistent environments such as rivers (20). In addition, fishes show a variety of body form associated with functions such as swimming and feeding to overcome different habitats and lifestyles (10, 21). The body shape can even display the lifestyles of a fish. Therefore, based on the diversity of the habitat features or lifestyles, the degree of a biological structure can show a higher plasticity (22), e.g. those fishes with a generalized body shape, are fusiform with a pointed head and forked tail.